Edge-Contact Geometry and Anion-Deficit Construction for Activating Ultrathin MoS₂ on W₁₇O₄₇ in the Hydrogen Evolution Reaction

Rational design and precise fabrication of catalysts with high active site exposure and efficient charge transport are highly desirable but challenging. Herein, we report a unique strategy to construct well-defined and mixed-dimensional W₁₇O₄₇-MoS₂ heterostructures, where ultrathin MoS₂ nanolayers vertically rooted onto W₁₇O₄₇ nanowires in edge-contact geometry. The in situ etching approach simultaneously created high accessible anion-deficit sites for refined electronic structures and intimate heterointerface for spatial charge-flow-steering. The best W₁₇O₄₇-MoS₂, with optimized MoS₂ loading, exhibited a MoS₂ mass activity 116-fold higher than that of pure MoS₂ in electrocatalytic hydrogen evolution reaction. Density functional theory calculations unveiled that low-coordination sites and intimate interfaces induced the synergy of interface-O and edge-Mo atoms, substantially regulating the electron distribution of active sites in the critical hydrogen activation step. This work not only provided a platform for understanding the origin of catalytic activity, but also brought instructive design criteria for constructing heterostructures in catalysis, photonics, and electronics.